To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
In order to meet the increasing demand for radio data traffic, wireless communication systems are developing to be able to support a higher data transfer rate. The 4G system which is widely used in recent years focuses on the technology development for improving spectral efficiency in order to increase the data transfer rate. However, this improvement in the spectral efficiency cannot alone cope with the increasing demand for the radio data traffic.
As a solution to the above-described problem, a method of using a very broad frequency band is employed. The frequency band used in current mobile communication cellular systems is generally lower than 10 GHz and it is difficult to guarantee a wide frequency band. Therefore, there is a need for a wideband frequency in a higher frequency band. However, as a frequency for radio communication increases, a radio wave path loss increases. To this end, a reaching distance of radio waves is relatively shortened, and accordingly, service coverage is reduced. To solve this problem, a beamforming technique is used as one of the important techniques for mitigating the radio wave path loss and increasing the reaching distance of the radio waves.
The beamforming is divided into transmission beamforming which is performed in a transmitting end and reception beamforming which is performed in a receiving end. In general, the transmission beamforming increases directivity by focusing a reaching area of radio waves on a specific direction using a plurality of antennas. In this case, a collection of a plurality of antennas may be referred as an antenna array and each of the antennas included in the array may be referred to as an array element. The antenna array may be configured in various forms such as a linear array, a planar array, and the like. The transmission beamforming increases a transfer distance by increasing directivity of signals. Furthermore, since signals are rarely transmitted in other directions than the directed direction, signal interference in other receiving ends is greatly reduced. The receiving end may perform beamforming reception signals using a reception antenna array. The reception beamforming increases sensitivity of reception signals entering in a corresponding direction by focusing the reception of radio waves in a specific direction, and provides a gain of blocking interference signals by excluding signals entering in directions other than the corresponding direction from the reception signals.
As described above, in order to guarantee a wide frequency band, the introduction of a super-high frequency, that is, an mmWave system is expected, and, in this case, the beamforming technique is considered to overcome the radio wave path loss. Further, beamforming may be applied to a synchronization signal and a reference signal which are transmitted from a base station. Accordingly, a method for searching neighboring cells by considering a transmission beam of a base station and a reception beam of a terminal should be proposed.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.